A bacterial laccase from marine microbial metagenome exhibiting chloride tolerance and dye decolorization ability

Abstract

Laccases are blue multicopper oxidases with potential applications in environmental and industrial biotechnology. In this study, a new bacterial laccase gene of 1.32 kb was obtained from a marine microbial metagenome of the South China Sea by using a sequence screening strategy. The protein (named as Lac15) of 439 amino acids encoded by the gene contains three conserved Cu(2+)-binding domains, but shares less than 40% of sequence identities with all of the bacterial multicopper oxidases characterized. Lac15, recombinantly expressed in Escherichia coli, showed high activity towards syringaldazine at pH 6.5-9.0 with an optimum pH of 7.5 and with the highest activity occurring at 45 °C. Lac15 was stable at pH ranging from 5.5 to 9.0 and at temperatures from 15 to 45 °C. Distinguished from fungal laccases, the activity of Lac15 was enhanced twofold by chloride at concentrations lower than 700 mM, and kept the original level even at 1,000 mM chloride. Furthermore, Lac15 showed an ability to decolorize several industrial dyes of reactive azo class under alkalescent conditions. The properties of alkalescence-dependent activity, high chloride tolerance, and dye decolorization ability make the new laccase Lac15 an alternative for specific industrial applications.

An acid-stable bacterial laccase identified from the endophyte Pantoea ananatis Sd-1 genome exhibiting lignin degradation and dye decolorization abilities

“…The first structure of a bacterial laccase was of that from Bacillus subtilis, named CotA laccase (Enguita et al 2003). The most recent report of a bacterial laccase is from a marine microbial metagenome, which also exhibits dye decolorization ability (Fang et al 2011). Because of the extreme thermostability and pH stability of prokaryotic enzymes compared to eukaryotic enzymes, bacterial laccases may be ideal for industrial applications.…”

Characterization of a Novel Laccase-producing Bacillus sp. A4 and its Application in Miscanthus Degradation

“…Furthermore, it was reported that bacterial laccases showed superior tolerance to various harsh environments. Fang et al (2011) isolated a bacterial laccase from a marine microbial metagenome that exhibited chloride tolerance and dye decolorization ability. The spore laccase of Bacillus licheniformis LS04 was found to be quite stable at high temperatures, showed no loss of laccase activity after 10 days of incubation at pH 9.0, and demonstrated organic solvent tolerance (Lu et al 2012).…”

Emerging Strategies and Integrated Systems Microbiology Technologies for Biodiscovery of Marine Bioactive Compounds

“…Sequenced-based screening has been used together with NGS technologies in the identification of PKS and NRPS clusters from a number of cultured strains [177]. Further to this, sequence-based analysis of marine metagenomic libraries has to date revealed the presence of a number of enzymes including peptidases [178], alkane hydroxylases [179], laccase [15], and a fumarase [17]. In the case of the peptidases, the Sargasso Sea Whole Genome Sequence (WGS) dataset, involving a total of 1.045 billion base pairs of metagenomic DNA sequence, with over 1.2 million protein encoding ORFs [180], was analyzed by Cotrell and coworkers [178] by using BLAST, in the identification of potential hydrolases.…”